Tube rolling mill



Nov. 14, 1939-.` R. E. BROCK TUBE ROLLING MILL Filed July 6, 1938 2 Sheets-Sheet 1 NVENTUR ATJURMSK Nov. 14, 1939. R. E. BROCK 2,179,918

TUBE ROLLING MILL l Filed July e', 1938 2 sheets-sheet 2 Wwf/ELI@ ('aggg) TTUHNEK Patented Nov. 14, 1939 g UNITED STATES PATENT OFFICE 5 Claims.

My invention is an improvement in the manufacture of seamless tubing and involves the method and means for simultaneous interior and ex` terior reduction, elongation and smoothing of the wall of a pierced billet or tubular work piece, in transit through the mill.

Instead of usual standard practices employing outer compressing rolls and a uniform diameter mandrel or a mere shouldered enlarging mandrel, I utilize a surrounding group of diagonally acting skew rolls each having an initial taper and a truly cylindrical extension with an interposed co-operating mandrel of special construction.

' Such mandrel is so made as to provide, in combination with the skew rolls, three successive zones of mutual external and internal treatment, to wit, (l) an entering preliminary inwardly and outwardly applied gauge reducing zone, (2) an abruptly adjacent final'inwardly applied reducing zone, and (3) an inwardly and outwardly ap- Figs. 4 to 7 inclusive are sectional detail views of the blank in progress, illustrating successive steps or zones of treatment by the skew rolls and co-operating mandrel;

Fig. 8 is a cross sectional view on 'the line VIII-VIII of Fig, 1 through the skew rolls but showing reinforcement of each by backing up rolls.

Referring to the drawings the mill is generally of conventional construction, utilizing a drive housing A the main driving gear of which is connected by shaft l2 with any suitable prime mover or source of power, as a motor B. The reduced speed gears of the drive housing are connected by shafts 3l and universal couplings 4 with the spindles 5 which are similarly connected at 6 with the shafts 'I of the several skew rolls, mounted in roll housing C. Beyond the roll housing C is mandrel (Cl. SII-13) ing the outer surrounding group, in suitable adjustable bearings, each being sufficiently diagonal to the normal line of the main pass to effect longitudinal feed of the work piece co-extensive with their external wall-reducing function. At their forward or entering ends each roll I ispreferably initially rounded at the terminal of a tapered substantially half length portion II, beyond which the roll is continuously cylindrical as at I2.

The mandrel I3 is generally cylindrical, having a front preliminary entering extension I4 provided with a taper corresponding generally to that .of front section II of the skew rolls; a midway abruptly tapered annular shoulder I5; and a truly cylindrical rear extension I6 parallel with the section I2 of the skew rolls.

The mandrel I3 engages by a terminal rear socket I'I, or otherwise, with the mandrel bar I8, the rear end of which is removably resisted by the thrust bracket D, for separation and from the mandrel with the finished tube. Such parts are well known in the art.

The gears of the drive housing A are of any suitable arrangement for transmission of power and desired speed from the prime mover B to the skew rolls I0, either direct as shown, or with an intervening speed reducer of `suitable type, depending on working conditions.

Thus, as in Fig. 3 I show a cross section of the drive housing in which the drive shaft 2 is provided with a pinion I9 engaging the several gears of each shaft 3 for simultaneous rotation of the several skew rolls I0 through the converging spindles 5 and their, universal joint connections.

The tubular blank or work piece E having been positioned as in'Fig. 4 is initially gripped by tn e tapered portions II of the skew rolls which r0- tate and feed itforwardly with an initial tapered external compression. The blank is thus advanced until its' approaching end engages the active portion of the tapered terminal I4 o1' I3, 'resisted by bar I8 and thrust bracket D.

Further forward movement of the blank by and between the tapered portions of the skew rolls and over the tapered end I4 of the mandrel effects simultaneous substantially equal external and internal reduction and gradual progressive thinning of the annular wall up to the annular shoulder of the mandrel, as in Fig. 5.

Thereafter, while still confined by the taper faces II of the skew rolls, the blank is abruptly enlarged interiorly to its final inside diameter,

and with its outside diameter already nally re-- duced, just prior to passing onto the cylindrical portion I6 of the mandrel and between the similar portions I2 of the skew rolls, as in Fig. 6.

Then the tube in progress is smoothed and polished to its final nished surfaces in uniform continuous ilnal condition.

I! desired, the tube may then be subjected to additional treatment for straightening, sizing or further reduction or to cold drawing, as is well 10 known to those skilled in the art.

'I'he simultaneous reduction of outside diameter and increase o1 inside diameter of the work piece and its resulting elongation, with accompanying condensation and ilnal smoothing and polishing oi' the flmshed tube, continues until its rear end has passed entirely lbeyond the mandrel. It will thus be seen that the pass ofV themill narrows or decreases in external diameter and increases in internal diameter until it enters the third or smoothing zone.

'I'he thrust bracket is then withdrawn and the finished tube, mandrel bar, and mandrel are removed and separated, such bar and another mand rel being then replaced for the next. similar operation.

Trial operations of the mill have demonstrated its success and of the improved method of rapid-4 1y forming seamless tubing, as disclosed herein.

Thus, with an original pierced billet or work piece of the following dimensions, to wit:

Inches Outside diameter 1.223 Inside diameter .'750 Wall thickness .2365 Area bf wsu .7315.

the resulting tubing, with greatly increased elongation, was:

Outside diameter 1.062 Inside diameter .876 Wall thickness .093 Area of wall .282

with the following relative or proportionate '45 changes, compared to the dimensions of the blank:

Per cent Reduction in area 61.4

` Reduction in wall thickness 60.6

50 Increase 1n1ength 112.5

While properly proportioned skew rolls are. ordinarily quite efficient for usual normal oper l. Means for forming seamless tubing from a Inches pierced billet or work piece consisting of a plurality of outer rotatable reducing skew rolls each having a front preliminary uniformly tapered portion and a finishing cylindrical portion, and an inner rotatable expanding mandrel having a uniformly tapered end merging into an intermediate abruptly enlarged annular shoulder and a Irear maximum diameter cylindrical portion parallel lwith and in iinal operative relatlonto the cylindrical portion of the outer rolls with an intervening finishing pass therebetween.

2. Means for forming seamless tubing from a pierced billet or work piece consisting of a plurality of outer rotatable reducing skew rolls each having a front preliminary uniformly tapered portion and a nishing cylindrical portion, back up rolls for the skew rolls, and an inner rotatable expanding mandrel having a uniformly,tapered end merging into an 'intermediate abruptly en-4 larged annular shoulder and a rear maximum diameter cylindrical portion parallel with and in nal operative relation to the cylindrical portion of the outer rolls with an intervening finishing pass therebetween.

3. Means for forming seamless tubing from a pierced billet or work piece 'consisting of a plurality of outer rotatable reducing skew rolls each having a front preliminary uniformly tapered portion and a iinishing cylindrical portion, and an inner rotatable expanding mandrel having a uniformly tapered end merging into an" intermediate abruptly enlarged annular shoulder coextensive in its extreme diameter with a rear maximum diameter cylindrical portion, said ta- -pe'red'end nd annular shoulder opposing preshaving a front preliminary uniformly tapered portion and a nishing cylindrical portion, and an inner rotatable expanding mandrel having a umformly tapered end merging into an intermediate abruptly enlarged annular tapered shoulder co-extensive in its extreme diameter with a rear maximum diameter cylindrical portion, said tapered end and annular shoulder opposing pressure of the tapered portions of the skew rolls and the 'cylindrical portions. of the mandrel opposing pressure of the cylindrical portions of the skew rolls whereby to effect simultaneous external reduction and internal increase of diameter of the piece with iinal smoothing.

5. The construction as in claim 4 characterized by reinforcement, for the skew rolls in the form of a series of.outer'resisting back up rolls in contact with the several skew'rolls.

RICHARD E. BROCK. 

